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Ultrasonic Control of Ceramic Membrane Fouling Caused by Silica Particles and Dissolved Organic Matter

Chen, Dong
http://rave.ohiolink.edu/etdc/view?acc_num=osu1109363214

Abstract Details

2005, Doctor of Philosophy, Ohio State University, Civil Engineering.
This study systematically investigated the mechanism and efficiency of the ultrasonic control of gamma-alumina ceramic membrane fouling caused by silica particles and dissolved organic matter (DOM). Ultrasound at 20 kHz was applied to a cross-flow filtration system. First, ultrasonic cleaning was explored with filtration of silica particles to investigate influence of both particle characteristics and ultrasonic factors on cleaning. Experimental results indicated that more effective control of fouling occurring at low particle concentrations, hydrophilic particles, and large particle sizes based on measurements of sound wave intensity, images of the cavitation region, and force balance analysis of a particle deposited on the membrane. In addition to the effect of particle characteristics, ultrasonic factors affecting membrane cleaning were explored. Optimal cleaning occurred when the membrane was outside but close to the cavitation region. However, damage in the form of pits and cracks were found when the membrane was within the cavitation region. An increase in the filtration pressure resulted in less improvement in permeate flux of ultrasound. Furthermore, pulsed ultrasound with short pulse intervals resulted in a relative permeate flux improvement close to that of continuous sonication. Second, besides sonophysical cleaning of particle fouled membranes, membrane cleaning was also explored by studying sonochemical reactions of DOM. Property changes of Aldrich and Pahokee peat DOM at different ultrasonic frequencies and energy densities were systematically investigated. Exposure of DOM to ultrasound resulted in decreases in hydrophobicity, aromaticity, and molecular weight, while DOM acidity increased. However, at low ultrasonic frequency (20 kHz) and low energy density, sonochemical transformation of DOM was insignificant. Finally, the effect of solution chemistry on ultrasonic control of membrane fouling caused by DOM and silica particles was examined. Experimental results indicated that more effective control of membrane fouling occurred at high pH, low ionic strength, and in the absence of divalent cations, due to stronger electrostatic repulsion among DOM macromolecules, silica particles, and the membrane. The decrease of the DOM rejection rate by ultrasound may be explained by the decreased steric exclusion effect, because ultrasound partially released membrane pore blocking and/or partially removed the foulant layer from the membrane surface.
Linda Weavers (Advisor)
207 p.
Engineering, Environmental
ultrasound; ultrafiltration; membrane cleaning; membrane fouling; luminol; cavitation; pitting; natural organic matter; dissolved organic matter; Aldrich; Pahokee; 13C NMR; aromaticity; oxidation

Recommended Citations

Citations

  • Chen, D. (2005). Ultrasonic Control of Ceramic Membrane Fouling Caused by Silica Particles and Dissolved Organic Matter [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1109363214

    APA Style (7th edition)

  • Chen, Dong. Ultrasonic Control of Ceramic Membrane Fouling Caused by Silica Particles and Dissolved Organic Matter. 2005. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1109363214.

    MLA Style (8th edition)

  • Chen, Dong. "Ultrasonic Control of Ceramic Membrane Fouling Caused by Silica Particles and Dissolved Organic Matter." Doctoral dissertation, Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1109363214

    Chicago Manual of Style (17th edition)

osu1109363214
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© 2005, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.